linux-kernel - [PATCH v5 0/7] KVM: Support PUD hugepages at stage 2

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Date:   Mon,  9 Jul 2018 15:38:27 +0100
From:   Punit Agrawal <punit.agrawal@....com>
To:     kvmarm@...ts.cs.columbia.edu
Cc:     Punit Agrawal <punit.agrawal@....com>,
        linux-arm-kernel@...ts.infradead.org, marc.zyngier@....com,
        christoffer.dall@....com, linux-kernel@...r.kernel.org,
        suzuki.poulose@....com, will.deacon@....com
Subject: [PATCH v5 0/7] KVM: Support PUD hugepages at stage 2

This series is an update to the PUD hugepage support previously posted
at [0]. This patchset adds support for PUD hugepages at stage
2. This feature is useful on cores that have support for large sized
TLB mappings (e.g., 1GB for 4K granule).

The biggest change in this version is to replace repeated instances of
walking the page tables to get to a leaf-entry with a function to
return the appropriate entry. This was suggested by Suzuki and should
help reduce the amount of churn resulting from future changes. It also
address other feedback on the previous version.

Support is added to code that is shared between arm and arm64. Dummy
helpers for arm are provided as the port does not support PUD hugepage
sizes.

The patches have been tested on an A57 based system. The patchset is
based on v4.18-rc4. The are a few conflicts with the support for 52
bit IPA[1] due to change in number of parameters for
stage2_pmd_offset().

Thanks,
Punit

v4 -> v5:
* Patch 1 - Drop helper stage2_should_exec() and refactor the
  condition to decide if a page table entry should be marked
  executable
* Patch 4-6 - Introduce stage2_get_leaf_entry() and use it in this and
  latter patches
* Patch 7 - Use stage 2 accessors instead of using the page table
  helpers directly
* Patch 7 - Add a note to update the PUD hugepage support when number
  of levels of stage 2 tables differs from stage 1

v3 -> v4:
* Patch 1 and 7 - Don't put down hugepages pte if logging is enabled
* Patch 4-5 - Add PUD hugepage support for exec and access faults
* Patch 6 - PUD hugepage support for aging page table entries

v2 -> v3:
* Update vma_pagesize directly if THP [1/4]. Previsouly this was done
  indirectly via hugetlb
* Added review tag [4/4]

v1 -> v2:
* Create helper to check if the page should have exec permission [1/4]
* Fix broken condition to detect THP hugepage [1/4]
* Fix in-correct hunk resulting from a rebase [4/4]

[0] https://www.spinics.net/lists/arm-kernel/msg663562.html
[1] https://www.spinics.net/lists/kvm/msg171065.html

Punit Agrawal (7):
  KVM: arm/arm64: Share common code in user_mem_abort()
  KVM: arm/arm64: Introduce helpers to manupulate page table entries
  KVM: arm64: Support dirty page tracking for PUD hugepages
  KVM: arm64: Support PUD hugepage in stage2_is_exec()
  KVM: arm64: Support handling access faults for PUD hugepages
  KVM: arm64: Update age handlers to support PUD hugepages
  KVM: arm64: Add support for creating PUD hugepages at stage 2

 arch/arm/include/asm/kvm_mmu.h         |  60 +++++
 arch/arm64/include/asm/kvm_mmu.h       |  47 ++++
 arch/arm64/include/asm/pgtable-hwdef.h |   4 +
 arch/arm64/include/asm/pgtable.h       |   9 +
 virt/kvm/arm/mmu.c                     | 289 ++++++++++++++++++-------
 5 files changed, 330 insertions(+), 79 deletions(-)

-- 
2.17.1